The Effect of Stretching on UHWMPE Microporous Film by Thermally Induced Phase Separation Method

Abstract

UHMWPE microporous membranes were prepared via thermally induced phase separation(TIPS) combining with stretching. TIPS method was adopted to resolve processing difficulties of UHMEPE, and the subsequent stretching was used to optimize pore structure. The preparation process utilized liquid paraffin (LP) as the diluent. The effect of different stretching ratios on pore structure was investigated through SEM, XRD and mercury intrusion test. The results indicated that stretching process not only greatly improved the pore size uniformity and pore distribution uniformity, but also had a great influence on pore size controlling. When the stretching ratio was lower than 80%, the pore size was concentrated in nano-region which pore size distribution was around 0.02-0.03 μm. While the stretching ratio was larger than 80%, due to bridging breakage and liquid paraffin movement, pore size was concentrated in the micron area where pore size mainly distributed around 1μm, which had a practical significance for controlling the pore size of membranes in industrial production. And it’s obtained that at the same concentration of UHMWPE, the microporous membranes prepared in this study have more uniform pore structures than those reported previously.